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CHAPTER V".
MACHINE    T-QOLS.

THE pattern maker, moulder, and smith having supplied us
with rough castings and forgings, it is now necessary to finish
these articles truly before passing t^em on t6 the erector. After
marking or measuring-ofT, certain portions of nietal have to be                      I*

removed by hand or machine tools. The remainder of our work
will then consist of—Marking-off, or indicating the finished outline
by a boundary mark; Machining, or removing superfluous
material by automatic or semi-automatic machine power; and
Fitting^ which is the finishing of certain parts by hand power,
usually the chisel and file.

Machining has always tended to gradually usurp fitting by
hand, .and its advance is so rapid at present as entirely to take
the place of handwork for such articles as are to be repeated ; in
such instances manufacturers have special machines designed.
Even in unrepeated work a much larger quantity is done by
machine than hitherto, perhaps most of all by the extended use
of such tools as milling machines,

As so much depends on the perfection of a machine tool itself
{the workmen merely ' setting9 the work and arranging speeds),
a thorough knowledge of these machines is necessary, so as to
appreciate their capabilities and enable us to design work to suit
them.

The next chapter has been reserved for the operations of
marking-orT, machining, and erecting, the present being devoted
to the Machines themselves, which may be classified as Lathes /
Planing, Shading and Slotting Machines; Baring and Drilling
Machines ; and Milling Machines.

Of course there are many general varieties of each class, and
each variety is again varied to suit special needs. Thus, as
regards drilling machines, most inland workshops are supplied